https://developer.mozilla.org/en-US/docs/Web/API/RTCDTMFSender/canInsertDTMF
RTCDTMFSender: canInsertDTMF property - Web APIs | MDN
The canInsertDTMF read-only property of the RTCDTMFSender interface returns a boolean value which indicates whether the RTCDTMFSender is capable of sending...
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